The Hoya ND 4 reduces light by the equivalent of 2 stops. For photographers, ND filters mean precise control of the amount of light that passes through the lens to allow greater creative control of exposure. For video content creators, ND filters are very helpful in adjusting shutter speeds to match frame rates while maintaining the depth of field of the footage. PROND filters use HOYA's clear optical glass mounted in a lightweight, precision-machined aluminum frame. The frame has a front filter thread so you can attach additional filters or a lens capWith HOYA's exclusive ACCU-ND technology, uniform reduction of light in the visible and IR spectrum is achieved. As a result, the photographer does not have to worry about color shift problems when using HOYA ND filters under different shooting conditions.